A superconducting magnet is an electromagnet composed of a coil formed by winding a wire formed of a superconductor around a predetermined center axis. The superconducting magnet device is driven at high current density by utilizing a superconducting characteristic of zero electric resistance. Therefore, it is possible to generate a high magnetic field which is hardly generated by a general electromagnet.
In order to generate a larger magnetic field, a superconducting magnet device including a plurality of superconducting coils disposed concentrically with each other is known (for example, refer to Markiewicz et al., IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY, VOL. 22, NO. 3, JUNE 2012, 4300704 (Document 1) and Yanagisawa et al., Journal of Magnetic Resonance 249 (2014) 38-48 (Document 2)). Superconducting magnet devices described in Documents 1 and 2 each include a plurality of outer superconducting coils, and a plurality of inner superconducting coils. The plurality of outer superconducting coils are each formed by winding a round wire formed of a metal-based superconductor around a center axis. The plurality of inner superconducting coils are each formed by winding a tape wire including an oxide-based superconductor around a center axis.